package com.zy.jike.数据结构与算法之美.基本数据结构.linkedlist;

/**
 * @ClassName SinglyLinkedList
 * @Description 单链表的插入，删除，查找
 * 链表中存储的是int类型的数据
 * @Author peppers
 * @Date 2020/3/21$ 11:53 上午
 * @Version 1.0
 **/
public class SinglyLinkedList {

    public static class Node {
        private int data;
        private Node next;

        public Node(int data, Node next) {
            this.data = data;
            this.next = next;
        }

        public int getData() {
            return data;
        }
    }

    public static Node createNode(int value) {
        return new Node(value, null);
    }
    private Node head= null;

    public Node findByValue(int index){
        Node p = head;
        int pos = 0;
        while(p != null && pos != index){
            p = p.next;
            ++pos;
        }
        return p;
    }

    //无头结点
    //表头部插入
    //这种操作将于输入的顺序相反，逆序
    public void insertToHead(int value){
        Node newNode = new Node(value,null);
        insertToHead(newNode);
    }

    public void insertToHead(Node newNode){
        if(head == null){
            head = newNode;
        }else {
            newNode.next = head;
            head = newNode;
        }
    }

    //顺序插入
    //链表尾部插入
    public void insertTail(int value){
        Node newNode = new Node(value,null);
        //空链表，可以插入新节点作为head，也可以不操作
        if(head == null){
            head = newNode;
        }else {
            Node q = head;
            while (q.next != null){
                q = q.next;
            }
            newNode.next = q.next;
            q.next = newNode;
        }
    }
    public void insertAfter(Node p, int value) {
        Node newNode = new Node(value, null);
        insertAfter(p, newNode);
    }

    public void insertAfter(Node p, Node newNode) {
        if (p == null) return;

        newNode.next = p.next;
        p.next = newNode;
    }

    public void insertBefore(Node p, int value) {
        Node newNode = new Node(value, null);
        insertBefore(p, newNode);
    }

    public void insertBefore(Node p, Node newNode) {
        if (p == null) return;
        if (head == p) {
            insertToHead(newNode);
            return;
        }

        Node q = head;
        while (q != null && q.next != p) {
            q = q.next;
        }

        if (q == null) {
            return;
        }

        newNode.next = p;
        q.next = newNode;

    }
    public void deleteByNode(Node p) {
        if (p == null || head == null) return;

        if (p == head) {
            head = head.next;
            return;
        }

        Node q = head;
        while (q != null && q.next != p) {
            q = q.next;
        }

        if (q == null) {
            return;
        }

        q.next = q.next.next;
    }

    public void deleteByValue(int value) {
        if (head == null) return;

        Node p = head;
        Node q = null;
        while (p != null && p.data != value) {
            q = p;
            p = p.next;
        }

        if (p == null) return;

        if (q == null) {
            head = head.next;
        } else {
            q.next = q.next.next;
        }

        // 可重复删除指定value的代码
        /*
           if (head != null && head.data == value) {
           head = head.next;
           }
           Node pNode = head;
           while (pNode != null) {
           if (pNode.next.data == data) {
           pNode.next = pNode.next.next;
           continue;
           }
           pNode = pNode.next;
           }
         */
    }

    public void printAll() {
        Node p = head;
        while (p != null) {
            System.out.print(p.data + " ");
            p = p.next;
        }
        System.out.println();
    }

    //判断true or false
    public boolean TFResult(Node left, Node right){
        Node l = left;
        Node r = right;

        boolean flag=true;
        System.out.println("left_:"+l.data);
        System.out.println("right_:"+r.data);
        while(l != null && r != null){
            if (l.data == r.data){
                l = l.next;
                r = r.next;
                continue;
            }else{
                flag=false;
                break;
            }

        }

        System.out.println("什么结果");
        return flag;
       /* if (l==null && r==null){
           System.out.println("什么结果");
           return true;
        }else{
           return false;
        }*/
    }

    //　判断是否为回文
    public boolean palindrome(){
        if(head == null){
            return false;
        }else {
            System.out.println("开始寻找中间节点");
            Node p = head;
            Node q = head;
            if(p.next == null){
                System.out.println("只有一个元素");
                return true;
            }while (q.next != null && q.next.next != null){
                p = p.next;
                q = q.next.next;
            }
            System.out.println("中间结点"+ p.data);
            System.out.println("开始执行奇数结点的回文判断");
            Node leftLink = null;
            Node rightLink = null;
            if(q.next == null){
                //p一定为整个链表的中心，且节点数目为奇数
                rightLink = p.next;
                leftLink = inverseLinkList(p).next;
                System.out.println("左边第一个节点"+leftLink.data);
                System.out.println("右边第一个节点"+rightLink.data);
            }else {
                // p q 均为中点
                rightLink = p.next;
                leftLink = inverseLinkList(p);
            }
            return TFResult(leftLink,rightLink);
        }
    }

    /**
     *
     * @author peppers
     * @date 2020/3/22
     * @param [p]
     * @return com.zy.jike.数据结构与算法之美.基本数据结构.linkedlist.SinglyLinkedList.Node
     */
    public Node inverseLinkList_head(Node p){
        //Head为新建的一个头结点
        Node Head = new Node(9999,null);
        // p 为原来整个链表的头结点，现在Head指向整个链表
        Head.next = p;
        //带头结点的链表反转等价于从第二个元素开始重新头插法建立链表
        Node Cur = p.next;
        p.next = null;
        Node next = null;

        while (Cur != null){
            next = Cur.next;
            Cur.next = Head.next;
            Head.next = Cur;
            System.out.println("first"+Head.data);

            Cur = next;
        }
        //返回左半部分的中点之前的那个结点
        //从这点开始同步两边比较
        return Head;
    }

    /**
     *
     * @author peppers
     * @date 2020/3/22
     * @param [p]
     * @return com.zy.jike.数据结构与算法之美.基本数据结构.linkedlist.SinglyLinkedList.Node
     */
    public Node inverseLinkList(Node p){
        Node pre = null;
        Node r = head;
        System.out.println("z"+r.data);
        Node next = null;
        while (r != p){
            next = r.next;
            r.next = pre;
            pre = r;
            r = next;
        }
        r.next = pre;
        //返回左半边部分的中点之前的那个节点
        //从此处开始同步比较
        return r;
    }
    public static void main(String[]args){

        SinglyLinkedList link = new SinglyLinkedList();
        System.out.println("hello");
        //int data[] = {1};
        //int data[] = {1,2};
        //int data[] = {1,2,3,1};
        //int data[] = {1,2,5};
        //int data[] = {1,2,2,1};
        // int data[] = {1,2,5,2,1};
        int data[] = {1,3,5,3,1};

        for(int i =0; i < data.length; i++){
            //link.insertToHead(data[i]);
            link.insertTail(data[i]);
        }
        // link.printAll();
        // Node p = link.inverseLinkList_head(link.head);
        // while(p != null){
        //     System.out.println("aa"+p.data);
        //     p = p.next;
        // }

        System.out.println("打印原始:");
        link.printAll();
        if (link.palindrome()){
            System.out.println("回文");
        }else{
            System.out.println("不是回文");
        }
    }
}
